Ethambutol toxic neuroretinopathy in Bangladesh

ABSTRACT

Ethambutol is considered to have a relative lack of toxicity. In Bangladesh, out of a total of 350 patients receiving ethambutol [25 mg to 35 mg/kg daily] for tuberculosis, 20 [5.71%] developed neuroretinal toxicity. Ten [50%] of these patients had peripheral, four [20%] central, and six [30%] mixed visual field defects. Thirteen [65%] patients recovered, with or without additional treatment, after ethambutol was stopped, but seven [35%] had irreversible damage. In several of the patients who recovered, the visual improvement began only when hydroxycobalamin was administered following the discontinuation of ethambutol. One woman mistakenly received cyanocobalamin instead of hydroxycobalamin, leading to optic atrophy and an irreversible visual loss in her. We would like to warn against the use of cyanocobalamin in patients on ethambutol